package com.njtech.pet.utils;

import java.security.MessageDigest;
/**
 * Author:gm
 * Date:2020-03-11 17:00
 * Description:<Md5加密，处理密码>
 */
public class Md5Util {

    //这里主要是遍历8个byte，转化为16位进制的字符，即0-F
    private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for(int i = 0; i < b.length;i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    //这里是针对单个byte，256的byte通过16拆分为d1和d2
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    /**
     * 返回大写MD5
     *
     * @param origin
     * @param charsetname
     * @return
     */
    private static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname)) {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            }else{
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
            }
        }catch (Exception exception) {

        }
        return resultString.toUpperCase();
    }

    public static String MD5EncodeUtf8(String origin) {

        return MD5Encode(origin, "utf-8");
    }


    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};



    public static void main(String[] args) {
        //测试数据，成功
        //123
        //202CB962AC59075B964B07152D234B70
        String password = "123";
        String encoded =  MD5EncodeUtf8(password);
        System.out.println(password);
        System.out.println(encoded);
    }
}
